refactor(compiler): 拆分 oxide_emit 为独立 emit pass crate（依赖倒置）

crates/oxide_emit/src/stmt/basic/break_continue.rs

@@ -0,0 +1,42 @@
+use crate::{CompileCtx, Emitter};
+use oxide_ir::inst::Inst;
+
+impl Emitter {
+    pub(crate) fn emit_break_statement(
+        &self, stmt: &oxide_parser::BreakStatement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let break_label = if let Some(label) = &stmt.label {
+            let name = label.name.as_str();
+            let scope = ctx
+                .find_label(name)
+                .ok_or_else(|| format!("SyntaxError: Undefined label '{name}'"))?;
+            scope.break_label
+        } else if let Some(sw_label) = ctx.current_switch() {
+            *sw_label
+        } else {
+            let (bl, _) = ctx.current_loop().ok_or("break outside switch or loop".to_string())?;
+            *bl
+        };
+        ctx.inst(Inst::jmp(break_label));
+        Ok(None)
+    }
+
+    pub(crate) fn emit_continue_statement(
+        &self, stmt: &oxide_parser::ContinueStatement, ctx: &mut CompileCtx,
+    ) -> Result<Option<u8>, String> {
+        let continue_label = if let Some(label) = &stmt.label {
+            let name = label.name.as_str();
+            let scope = ctx
+                .find_label(name)
+                .ok_or_else(|| format!("SyntaxError: Undefined label '{name}'"))?;
+            scope.continue_label.ok_or_else(|| {
+                format!("SyntaxError: Illegal continue statement: '{name}' does not denote an iteration statement")
+            })?
+        } else {
+            let (_, cl) = ctx.current_loop().ok_or("continue outside loop".to_string())?;
+            *cl
+        };
+        ctx.inst(Inst::jmp(continue_label));
+        Ok(None)
+    }
+}